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If a platform does verification of memory init then it must be careful to use the same slot for resume that it booted from. This is accomplished by adding a context flag to indicate this is an S3 resume and that vboot should treat it differently than a normal boot. When this flag is set then the same slot that was booted is read from VBNV and re-used for the resume path, without adjusting any try flags. If this slot is B then the related context flag is set. This will allow the firmware updater to update the other (non-booted) slot and set flags indicating that on the next boot the updated slot should be tried, while still allowing suspend/resume to work with the existing firmware slot. This assumes that the last tried slot was successfully booted, which should be a safe assumption since the system was able to boot and then suspend. It isn't reliable to check last_fw_result for "success" status because that status is only set some time after boot when chromeos-setgoodkernel calls chromeos-firmwareupdate --mode=bootok and so it may still report a status of "trying" on resume depending on how soon after boot the suspend happened. It also avoids setting the vboot flag indicating that a slot choice was made in order to avoid altering the try counter on failure since this is explicitly not attempting to boot the new slot. BUG=chromium:577269 BRANCH=glados TEST=manually tested on chell: 1) ensure that booting from slot A resumes from slot A. 2) ensure that booting from slot B resumes from slot B. 3) do RW update while booted from slot A (so the flags are set to try slot B) and ensure that suspend/resume still functions properly using current slot A. 4) do RW update while booted from slot B (so the flags are set to try slot A) and ensure that suspend/resume still functions properly using current slot B. Change-Id: I500faef2b5d19a02f32839976354abf6d551c9f6 Signed-off-by: Duncan Laurie <dlaurie@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/328812 Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Here's what's what in the firmware/ directory. include/ lib/ These are the original structures and APIs used in the earliest Chromebooks and continuing through 2014. It never had a version as such to begin with, but we now refer to this implementation as "vboot1" or "vboot version 1.0". linktest/ stub/ These are stubs used to link the vboot1 libraries into host-side test executables so we can run some tests on the build machine instead of a Chromebook. 2lib/ In 2014 we began work on a new vboot API. The first step was just a refactoring and renaming of the verification API. The public functions and external headers that are exported for use by the Chrome OS firmware (or anything else that wants to use vboot) live in here. The internal structures and implementations go elsewhere. lib20/ This is an early implementation of the public (2lib/) API. It is binary-compatible with vboot1, so although the interface details are different, any existing on-device structures or signatures created by the vboot1 tools can be validated using this implementation. This was deployed slightly before it was ready. That's not a problem, thanks to the binary compatibility, but this directory will be abandoned Real Soon Now, except for the product support branches. lib21/ This is where the current development of the second-generation vboot API is taking place. It uses the public (2lib/) API, but will NOT be binary compatible with vboot1 structs. Because of the early release of the lib20 stuff, we're actually calling this lib21.